User interfaces have traditionally relied on input devices such as keyboards, which require physical manipulation by a user. Increasingly, however, it is desired to detect and monitor the physical positions and movements of users within a scene or environment. User motions and gestures can be used in some environments as user commands and inputs to automated systems. In particular, hand positions and gestures may be useful in providing input from a user to a computerized system. When detecting or analyzing a hand positions, it is useful to detect the fingers of the hand and their positions.